storing comments on the IGD-schema

I like Detlef's awk script to capture information on tags,
but I think it needs a bit more:
1. tags need to be associated with classes, since a tag may have different
semantic meanings in different classes; and
2. likewise, pointers need to be associated with a particular ?Class/tag,
since there can even be multiple pointers to the same class from different
tags within a single class -- each with different semantic meaning.
At the ACEDB Workshop, we demonstrated that it is possible to invoke Mosaic
from within ACEDB, and to pass it information on what class and tag are
currently selected, so that one could provide context sensitive help
on individual elements (?Class, tag, pointer, data value, etc.).
-John